302 Changes in the Muscle Cell of Xecturus 



stages. Minot, in 1890, called attention to this feature of cell life in the 

 following words: "In all tlie principal tissues of the body we meet 

 everywhere the same phenomenon of growth, namely, that with the increas- 

 ing development of the organism and its advance in age Ave find an 

 increase in the amount of protoplasm. We see that there is a certain 

 antithesis, we might almost say a struggle for supremacy, between the 

 nucleus and protoplasm. 



" We have then to state, as the general result of the studies which we 

 have just made, that the most characteristic peculiarity of advancing age 

 of increasing development, is the growth of protoplasm; the possession 

 of a large relative quantity of protoplasm is a sign of age." 



Whether this disparity in the muscle cell is due entirely to an increase 

 in the amount of cytoplasm, or whether there is in the later stages a 

 reduction in the amount of nuclear material, is uncertain. Bowman, 

 as early as 18-14, said: " It is doubtful whether the identical corpuscles 

 (nuclei) originally present remain through life, or whether successive 

 crops advance and decay during the progress of growth and nutrition." 

 Kaestner, go, 6, found that the nuclei in the muscle cells of the duck 

 elongate, become smaller and smaller until finally, in a very late stage, 

 they disappear. Maurer, 94, 580, states that the muscle nuclei in Sire- 

 don occupy at first a central position, later a part of them migrate to the 

 periphery, but those remaining undergo degeneration and disappear. 



While I have found no evidence of complete disintegration of the 

 nuclei, I am unable to say that it does not occur. The fact that in the 

 older stages the nuclei possess but little chromatin suggests that com- 

 plete chromatolysis may occur. 



It has long been known that the nuclei of the muscle cell undergo 

 striking changes in position during growth, but the meaning of these 

 movements has been scarcely considered. The only suggestion which 

 merits quoting is tluit by ]\IacCallum, 98, 211, who finds that in the human 

 embryo of 130-170 mm. the muscle fibres stop increasing in number and 

 that at this time the nuclei change in character from the vesicular, 

 centrally disposed, to the solid, peripherally placed, nuclei. MacCallum 

 suggests that there is possibly a relation between the position of the 

 nuclei and the power of the cells to produce new fibres. 



As pointed out in the descriptive portion of this paper, the nuclei 

 occupy an axial position at the time the first fibrillas are formed; as the 

 differentiation of fibrillse continues, from the inner toward the outer side 

 of the cell, there is a corresponding movement of the nuclei toward the 

 outer side. When the cell is completely filled with fibrillge the nuclei 



